In cargo transportation, in order to limit the position of objects such as cargos, a position-limiting device is often used. At present, a high-speed railway freight (using high-speed freight motor train unit) has competitive advantages of being faster than ordinary trains and having a lower cost than air transportation. In the states represented by France and Germany, the high-speed railway freight has been developed starting from services such as delivering express mails and packages.
A common manner for loading and securing cargos in a conventional railway freight (Luggage and Parcel Express Special Train) is described as follows. Cargos are loaded and unloaded by workers, parcels are loaded in bulk (on the floor of a cargo compartment) and are stacked in a joint-covering stacking type or a trapezoid stacking type, and instead of being secured, the stacked cargos are tightly pressed against each other. In order to secure cargos on the high-speed freight motor train unit, it is required to realize the modularized unitizing and the quick loading and securing of the cargos, to ensure the safety and reliability of the transportation. In order to achieve the quick loading and securing of the modularized and unitized unit in the cargo compartment, two functions are particularly required to be achieved along a running direction of the train, the first function is to manually convey the unitized unit in a track, and the second function is to longitudinally limit the position of the unitized unit after being pushed to a designated position. The first function requires that the position-limiting device can be turned down to avoid interfering with the conveying process, and the second function requires that the position-limiting device can be turned up to limit the position of the unitized unit and meet the strength requirement. Thus, in order to meet the requirements of the freight, especially the high-speed railway freight, it is necessary to make improvements to address the above defects of the conventional technology.